From the viewpoints of, for example, controlling organic solvent emission and reducing the amount of energy used in the production process, curable resin compositions containing a polar monomer such as an acrylate or a methacrylate have been regarded as an important technique in various applications such as adhesives, pressure-sensitive adhesives, coating agents, inks, sealing materials, and potting materials. In particular, in the electric and electronic field, downsizing and weight reduction of electric and electronic parts have progressed with development of digital technology. An improvement in performance associated with downsizing and film thinning has been required for the adhesives, pressure-sensitive adhesives, coating agents, sealers, inks, sealing materials, and potting materials used for such parts.
For example, a production process of precision parts such as electric and electronic parts sometimes includes a step of performing heating to 200° C. or higher (e.g., a step of mounting an electronic part on a substrate), and nonoccurrence of cracking and the like is required in such a step. Furthermore, heat is generated when electric and electronic parts are used. Therefore, the above materials are required to have not only flexibility but also sufficient strength against long-term heat history for the purpose of relaxing a stress generated as a result of thermal expansion of a substrate by using a sealing layer, an adhesive layer, or the like. In addition, adhesives and coating agents for optical materials are required to have high transparency.
Cured products satisfying such strength, transparency, and the like can be produced by employing a known technique relating to a curable resin composition obtained by adding a low-molecular-weight diene polymer having a methacryloyl group or an acryloyl group to a methacrylate or an acrylate (e.g., refer to PTL 1 and PTL 2). A technique relating to a photocurable resin composition containing a terminally functionalized hydrogenated polybutadiene is also known (refer to PTL 3 and PTL 4).
Such a curable resin composition is excellent in terms of producing a cured product having, for example, high flexibility, moistureproofness, waterproofness, and transparency. However, resin compositions having a higher curing rate and better workability have been required in recent years, and there has been a room for further improvement.